In April 2024, Vital announced an updated Mineral Resource Estimate for the Tardiff Upper Zone Deposit at Nechalacho Rare Earths Project, ~100km southeast of Yellowknife, Northwest Territories, Canada (to 30 January 2024). Tardiff is estimated to contain:
- 2.48 million tonnes of TREO within a total mineral resource of 213Mt at 1.17% TREO, a 79% increase over the previous MRE (February 2023).
- 623,000 tonnes of neodymium and praseodymium (NdPr), a ~49% increase over the previous MRE.
Table 1: Summary of the Mineral Resource Estimate for the Tardiff Upper Zone – Effective January 30, 2024
Key points
- Tardiff is a globally significant source of NdPr (Figure 1) with a shallow open-pit constrained MRE.
- It hosts a differential Nd+Pr: TREO ratio (~25%) compared with most peers.
- April 2024 MRE is informed by an integrated cost and recovery approach which employs a net metal revenue (NMR) cut-off based on projected cost and recovery factors;
- The new base resource estimate was constructed using first principles cost and metal recovery factors, and payability assumptions utilising peer and operational data to generate an NMR of C$115 per tonne and is reported within an optimised pit shell;
- Resource estimate for the Tardiff Upper Zone Deposit was created using drilling and assay results available as of 30 January 2024, unchanged from the previous MRE (31 December, 2022); and
- Vital expects to announce a further MRE update later in 2024 that will incorporate all drilling data completed post 2022.
The Tardiff MRE was compiled and is reported in accordance with the Australasian Code of Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC 2012 edition) and Chapter 5 of the ASX Listing Rules.
Globally important NdPr source
Figure 1: NdPr Grade (wt%) vs MRE NdPr (kt) (contained)
1. Base (’24): VML’s new 1.0x RF resource estimate (see Tables 1 and 6). RF [0.5] (’24) represents VML’s new resource estimate using 0.5x RF (see Tables 1 and 3). (’23) refers to VML’s former resource estimate published in February, 2023. NdPr = Nd2O3 + Pr6O1
Table 2. Mineral Resource Estimate Sensitivities [April 2024: Revenue Factors (1.0x: Base Case), and 0.5x]
Notes:
1. JORC (2012) definitions were followed for Mineral Resources.
2. Mineral Resources are estimated above a net metal revenue (NMR) value of C$115/t.
3. Mineral Resources are estimated using average long term metal prices and metallurgical recoveries as outlined in Section 3 of JORC Table 1, a mining cost of C$4.50/t moved, a processing cost of C$92/t milled, G&A costs of C$15/t milled, and transportation costs of C$70/t concentrate moved and C$115/t final product TREO moved.
4. Average bulk density is 2.80 t/m3.
5. Revenue is attributable to Nd2O3 and Pr6O11.
6. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
7. Totals may not add or multiply accurately due to rounding.
8. RF: Revenue Factor
Tardiff Mineral Resource Estimate
The Mineral Resource estimate for the Tardiff Upper Zone Deposit was created using drilling and assay results available as of 30 January 2024, unchanged from the previous MRE (31 December, 2022; Vital Metals, 2023a). Table 2 provides the full list of estimated rare earth elements. Five resource domain wireframes were modelled representing sub-horizonal layers and bounded considering geology and a nominal cut-off value of 0.7% TREO in Leapfrog Geo software (see Figure 2).
Table 3: Mineral Resources at the Tardiff Upper Zone – Effective Date January 30, 2024
Figure 2: Plan view showing the estimation domains
Analytical results for the 2023 infill drilling program at the Tardiff Upper Zone (Vital Metals, 2023b, 2023c, 2024) have been received; however, collar surveys remain outstanding and, as such, these holes have not been incorporated into this update. These results will be included in a future MRE to be performed upon completion of the assaying and receipt of all outstanding collar location surveys. The Competent Persons (CPs) have reviewed available analytical and geological results and confirm that, while local variations do occur, the global grade and tonnage estimates are unlikely to be materially affected by these results, and that they are, in general, confirmatory of the geology and mineralization.
The MRE has been classified in accordance with the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (JORC Code, 2012 Edition). The Tardiff Mineral Resource was classified as Measured, Indicated, and Inferred based on drill hole spacing, the reliability of data, geological confidence, and with consideration to the continuity of grade (Figure 3). Measured Mineral Resources were guided by a nominal drill hole spacing of approximately 25 m, Indicated Mineral Resource by a nominal drill hole spacing of approximately 50 m, and Inferred Mineral Resources by a nominal drill hole spacing of less than approximately 200 m. Small volumes with locally wider drill hole spacing were included in the Measured and Indicated volumes to maintain continuity of classification shapes.
Figure 3: Plan view showing the resource blocks at a C$115/t NMR cut-off within the pit shell, colour-coded by resource classification
Open Pit Mineral Resources have been reported from a block model re-blocked to parent blocks with 5 m x 5 m x 3 m in the X, Y, and Z dimensions within an optimized pit shell generated using Whittle software and a slope angle of 45°and a pit discard Net Value cut-off of C$115/t (see Figures 3 – 6). Net Value factors were developed for the purposes of resource reporting and key assumptions behind these factors are presented in Table 3.
Figure 4: Plan view showing the resource blocks at a C$115/t NMR cut-off within the pit shell, colour-coded by TREO grade
Figure 5: North-South cross-section (20 m thick) showing the resource blocks at a C$115/t NMR cut-off within the pit shell and the drill hole composites, colour-coded by TREO grade
Figure 6: East-West cross-section (20m thick) showing the resource blocks at C$115/t NMR cut-off within the pit shell and the drill hole composites, colour-coded by TREO grade
Table 4: Operating Cost Assumptions for Tardiff Upper Zone
Notes:
1. Open pit mining is reported at pit discard cut-off, which excludes mining costs of C$4.50/t.
Mineral Resource Sensitivity
Mineral Resource Net Value sensitivity is presented in Table 3 and illustrates that the estimate is relatively insensitive to cut-off value.
Table 5: Mineral Resource Sensitivity to Cut-off Value1
1. Tonnes and grades are expressed within a series of nested pit shells generated at a range of revenue factors (RF). RF = 1.0 is the base case Mineral Resource using an NMR value of C$115 per tonne.
2. NdPr refers to the sum of neodymium and praseodymium oxide, Nd2O3 + Pr6O11
